This invention relates to a welding control method using image processing, and more particularly to a welding control method suitable for welding a thick plate with a narrow groove.
A welding control method consists of a welding torch position control method for conducting the welding with the torch being strictly in alignment with the welding groove and a welding heat input control method for controlling the depth of the weld. The former includes contact type welding torch position control which employs a roller simulating a welding groove, and a method of controlling the relative position of a torch to a welding groove by photographing an arc, detecting illumination intensity of the photographed images at two points in the width direction of the welding groove, and controlling the position of the torch to align with the groove center, which is disclosed in Japanese Patent Laid-open Application No. 38669/1983.
The letter control method includes a method in which welding conditions are set in advance and welding is conducted while reproducing these conditions for control, and a welding controlling method in which welding heat input is controlled based on the detected temperature of the molten metal, which is described in Japanese Patent Laid-open Application Nos. 102375/1981, and 28679/1982.
However, all of these methods are only capable of conducting either positioning control or heat input control and there is no method for controlling both position and heat input simultaneously.
Demand for progress in work efficiency in the field of welding by reduction of labor and automation has recently increased; hence, narrow groove welding has been developed. In the case of narrow groove welding, if the weld penetration into material to be welded at the groove face is small, multilayer welding is liable to produce defects, and this creates need to provide welding control of high accuracy.